Via Park Avenue Peerage — Tinsley Mortimer and actress Emmy Rossum, along with Vogue, will co-host a party celebrating the release of New York Times Styles writer Tatiana Boncompagni’s new novel Gilding Lily (out on September 9th from William Morrow/Harper Collins) at the Tahari store on West Broadway. Also expected to attend are socialites Jennifer Creel, Christian Leone, and Lydia Fenet, among others. The book—the story of a suburban girl’s marriage to the scion of a Manhattan society family and subsequent struggle to re-enter the social scene after pregnancy ravages her figure and energy–is Ms. Boncompagni’s first novel. It’s a satirical take on her experiences in New York, both as a chronicler of social life and a participant. A mother of two, she told us the idea came to her as she sat at home after the birth of her first child, “Juxtaposing the glamour of the social scene and what you feel like when you have a child…I felt so bad about myself! I’d gone from going to these parties and wearing these beautiful dresses to reading up on what my friends were doing on New York Social Diary. And then when I started to venture out, no one was taking my picture.” Ms. Boncompagni—a descendant of Italian nobility and Pope Gregory XIII—has already caught some flack for a Cookie Magazine column she wrote about the trials of social mothers, but she maintains that, “It is a valid struggle to want to have an active social life and actually be a good mom.” Personally, we wouldn’t know, but she seems like a good sport—tongue-in-cheek promotional video can be found here.